# MCQs: Normal Probability

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Find the area under the standard normal curve between z=0 and z=3.

A. 0.4987

B. 0.9987

C. 0.4641

D. 0.0010

IQ test scores are normally distributed with a mean of 100 and a standard deviation of 15. An individual's IQ score is found to be 110. Find the z-score corresponding to this value.

A. -1.33

B. 1.33

C. -0.67

D. 0.67

The lengths of pregnancies of humans are normally distributed with a mean of 268 days and a standard deviation of 15 days. A baby is premature if it is born three weeks early. What percentage of babies are born prematurely?

A. 9.21%

B. 8.08%

C. 6.81%

D. 10.31%

The distribution of cholesterol levels in teenage boys is approximately normal with and (Source: U.S. National Center for Health Statistics). Levels above 200 warrant attention. Find the probability that a teenage boy has a cholesterol level greater than 225.

A 0.0718

B 0.0012

C 0.0336

D 0.0606

An airline knows from experience that the distribution of the number of suitcases that get lost each week on a certain route is approximately normal with ? = 15.5 and Ï? = 3.6. What is the probability that during a given week the airline will lose less than 20 suitcases?

A 0.4040

B 0.3944

C 0.1056

D 0.8944

Assume that blood pressure readings are normally distributed with and A blood pressure reading of 145 or more may require medical attention. What percentage of people have a blood pressure reading greater than 145?

A. 99.91%

B. 6.06%

C. 0.09%

D. 11.09%

Assume that the salaries of elementary school teachers in the United States are normally distributed with a mean of $32,000 and a standard deviation of $3000. If a teacher is selected at random, find the probability that he or she makes more than $36,000.

A. 0.1056

B. 0.0918

C. 0.4040

D. 0.9082

IQ test scores are normally distributed with a mean of 100 and a standard deviation of 15. Find the x-score that corresponds to a z-score of -1.645.

A. 79.1

B. 91.0

C. 82.3

D. 75.3

For the standard normal curve, find the z-score that corresponds to the 90th percentile.

A. 0.28

B 1.52

C 1.28

D 2.81

Find the z-scores for which 90% of the distribution's area lies between -z and z.

A.(-0.99,0.99)

B.(-1.645,1.645)

C.(-2.33,2.33)

D.(-1.96,1,96)

#### Solution Summary

The solution provides answers to multiple choice questions on normal probability. Relevant workings are also included.